Polyamide resin, also known as nylon, exhibits excellent chemical resistance, lubricity and toughness, but inferior notched impact resistance and dimensional stability. This limits its field of application. Polyamide resins are used for a variety of products, including football face guards, hammer handle gears, sprockets, journal bearings, casters, package strapping, automobile dome lights, power tool housings, automotive parts, business equipment and other industrial and home applications. Because of its widespread utility, numerous efforts have been made to improve the impact resistance of polyamide.
U.S. Pat. No. 4,174,358 discloses polyolefin rubber grafted with organic carboxylic acid or anhydride using an interfacial agent to increase the compatibility between the polyamide and polyolefin rubber. Increasing the compatibility between these compounds improved the impact strength of their blends. However, grafting of these compounds using an interfacial agent resulted in a lowering of the heat distortion temperature, making the resultant composition disadvantageous.
U.S. Pat. No. 4,496,690 discloses modification of acrylonitrile-butadiene-styrene (ABS) with acrylamide as an interfacial agent for ABS/nylon blends to improve impact strength, heat distortion temperature and dimensional stability of the polymer blends. However, products prepared according to this method exhibited poor cold impact strength (0 degrees, 1/8 inch, notched impact strength of 1 ft-lb/in.)
European Patent No. 202,214 discloses the use of maleic anhydride modified-styrene-acrylonitrile copolymer as the interfacial agent for ABS/nylon blends. This process had limitations in its formulation capacity as well. Where the carboxy (anhydride) content increased by 1 mole percent or decreased by 0.5 mole percent, the impact strength of the polymer blends decreased by one-half and the product yellowed.
Accordingly, it is an object of the present invention to provide polymer blend compositions which exhibit improved impact resistance and dimensional stability.
It is a further object of the present invention to provide novel polymer compositions which employ interfacial agents to improve the compatibility between polyamide and polymer resins, thereby enhancing the impact resistance of the resultant polymer composition. It is still another object of the present invention to provide novel polymer blend compositions with improved impact resistance by using as interfacial agents either carboxy (anhydride)-containing acrylonitrile-butadiene copolymer or carboxy (anhydride)-containing styrene-olefin block copolymer.
It is yet another object of the present invention to provide novel polymer blend compositions of a Nylon/ABS polyblend with improved impact resistance by using carboxylated nitrile rubbers.
The benefits of using the carboxylated nitrile rubbers in a polyblend of Nylon/ABS include an increase in the compatibility between the Nylon and ABS phase and an impact modification of the Nylon/ABS polyblend.